1. Field of the Invention
The present invention relates to an information providing system, an information providing device, an appropriateness judgment information generation method and an appropriateness judgment information generation process program in the information providing device for generating screen information configuring a screen of information displayed to a user in response to a request from a terminal device through a network on the basis of information registered in a database and for providing the screen information to a terminal device.
2. Discussion of the Related Art
One type of an information providing system is typically that generates a web page in response to a request from a terminal device such as a personal computer, connected to the internet, on the basis of data registered in a database and providing the web page to a terminal device.
Such a system includes, for example, as shown in an invention described in Japanese Unexamined Patent Publication No. 2002-342086, a web server and a database server in which a database management system such as a relational database management system (RDBMS) is incorporated. In a case where the web server receives a request from a terminal device, the web server issues a structured query language (SQL) through an application program interface (API) such as an open database connectivity (ODBC) or a JDBC from the web server program to acquire data from the DBMS. Then, the web server generates a web page on the basis of the data thus acquired and transmits the web page to a terminal device. Amass of web pages provided from a web server in such a manner is called a web site.
Meanwhile, as a web site for entrance into the Internet, a search engine, a web directory, or a portal site providing various information like “Infoseek (Registered Trademark)” is known. The top page of such a portal site plays an important role as a window to various services such as internet shopping, auction, reservation of accommodation facilities, blog, news, and stock quotation. Therefore, part of information of each service is shown in the top page (e.g. recommendation of product, introduction of blog, headline of news, stock quotation of a company that the user has assigned in advance, or the like). Such information is registered in a database respectively and updated as needed. Therefore, every time the web server receives a request from a terminal device, data are acquired from the database to thereby generate its top page.
However, because a number of accesses to the top page of portal sites reaches a massive number such as several millions to several tens of millions, if web servers access databases for every request, load to the web servers and database servers becomes excessive to thereby delay response to a terminal device.
Therefore, “cache” is ordinarily used in such portal sites in order to prevent the delay.
Specifically, for example, data acquired from the database is stored in a cache (herein after, data stored in a cache is also referred to as “cache data”), and an expiration date of the data is set up (e.g. three minutes since the data is stored in a cache). Upon receipt of a request from a terminal device, the web server first judges whether or not an expiration date of a cache elapses. In a case where the expiration date does not elapse, the web server reads out cache data. Meanwhile, in a case where the expiration date elapses, the web server instructs to acquire data to an API. Then when the data are acquired through the API, the web server updates the cache data and sets up an expiration date again. Because there is ordinarily few information shown on the top page 3. of a portal site, it is possible to reduce a number of accesses to the database by generating a web page in use of data stored in the cache within the expiration date. Therefore, it is possible to rapidly respond to terminal devices without applying load to web servers and database servers.
However, in a case where process delay in the API, process delay in DBMS and the like occur, and therefore data are not be acquired to thereby cause detection of an error such as a timeout, an expiration date of a cache is extended, and a web page is generated using cache data stored in the cache at present. As such, the web server can surely send its top page to terminal devices without lack of information even if a trouble occurs to a certain part.